JPH0475066B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] As shown in FIG. Coating agent pool 3
The present invention relates to a top-feed type direct reverse roll coater in which a web W is passed through a nip between both rolls 1 and 2 and a coating agent from a coating agent reservoir 3 is applied to the web W.

[Background technology]

In this type of roll coater, if the coating agent does not reach the solvent-free type but dries quickly, the coating agent adhering to the circumferential surface of the counter-rotating roll 2 from the coating agent reservoir 3 comes into contact with the web surface. In the meantime, it tends to dry out and become crusty. As a result, the nip distance between the rolls 1 and 2 is distorted either entirely or partially in the width direction of the rolls, and this increases over time, making it impossible to perform coating with high precision. The counter-rotating roll 2 must be washed frequently. Further, there was a problem in that the surface on which the coating agent was applied to the web surface became rough.

[Purpose of the invention]

The present invention has focused on this fact, and is capable of preventing the coating material from forming on the counter-rotating roll 2 by using an extremely simple method but exhibiting an outstanding effect, and as a result, coating the web W The surface on which the agent is applied can also be smoothed.

[Summary of the invention]

That is, the principle of the present invention is to supply a solvent to the circumferential surface of the counter-rotating roll 2 after scraping off the coating agent with the doctor 4, so that the coating agent adhering to the counter-rotating roll 2 is dissolved by this solvent. It is in the point that I made it.

The solvent may be an organic solvent depending on the coating agent, or ordinary water in the case of a water-soluble coating agent.

〔Example〕

FIG. 1 illustrates a roll coater according to the present invention, in which 1 is rotationally driven in the direction of arrow A to coat the web W.
This is the main role that guides the movement of the vehicle. Reference numeral 2 denotes a counter-rotating roll that is rotated in the opposite direction, that is, in the direction of arrow B, at a contact point P' with respect to the main roll 1. The main roll 1 and the counter-rotating roll 2 face each other with a predetermined nip interval, and a coating agent reservoir 3 is formed in the upper part between the rolls 1 and 2 to maintain a predetermined liquid level. Web W in the nip between 2
When passing through the web W, the coating agent from the coating agent reservoir 3 is applied to one side of the web W by a counter-rotating roll 2. At least one of the rolls 1 and 2 is a rubber-coated roll and has a speed ratio.The main roll 1 is driven to rotate at the coating speed, and the counter-rotating roll 2 is driven to rotate at the coating speed.
Rotates more slowly.

A doctor 4 is in contact with the circumferential surface of the counter-rotating roll 2 at a portion on the lower side in the roll rotation direction near the coating agent reservoir 3, and the coating agent is scooped up from the coating agent reservoir 3 onto the circumferential surface of the counter-rotating roll 2. The coating agent is scraped off by the doctor 4 and most of it is returned to the coating agent reservoir 3.

A solvent is supplied to the circumferential surface of the counter-rotating roll 2 between the point of action P of the doctor 4 and the contact point P' of the main roll 1.

As this solvent supply means 5, in the example shown in the figure, a solvent supply member 6 made of a roll is brought into contact with a portion of the circumferential surface of the counter-rotating roll 2 in the vicinity of a portion on the downstream side in the roll rotation direction from the point of action P of the doctor 4. A solvent reservoir 7 is formed in the upper part between the counter-rotating roll 2 and the solvent supplying member 6 to maintain a predetermined liquid level, and the molten liquid from the solvent reservoir 7 is distributed on the circumferential surface of the counter-rotating roll 2 in the width direction. It is continuously supplied in appropriate amounts over the years. Although this solvent supply member 6 is expected to be fixed, it may be one that rotates together with the counter-rotating roll 2.

Furthermore, as the solvent supply means 5, the above-mentioned solvent supply member 6 may be replaced with a roll and may be a bar-shaped fixed member, or furthermore, the solvent supply member 6 may be a spray nozzle as shown in FIG. The solvent may be sprayed onto the circumferential surface of the counter-rotating roll 2, and the solvent supply means 5 can be freely selected.

[Actions and effects of the present invention]

According to the roll coater according to the present invention as described above, a solvent (such as water or various organic solvents) suitable for dissolving depending on the properties of the coating agent is applied to the circumferential surface of the counter-rotating roll 2 on the doctor 4. It is supplied at a location on the downstream side of the point of action P in the roll rotation direction. Therefore, even if the quick-drying coating agent transfers from the coating agent reservoir 3 to the counter-rotating roll 2 and remains on the circumferential surface of the roll after being scraped off by the doctor 4, the coating agent will remain on the circumferential surface of the roll. The remaining coating agent will be dissolved by the solvent and will not dry into a thin film. As a result, the circumferential surface of the counter-rotating roll 2 is always wetted with solvent and comes into contact with the coated surface of the web W passing through the nip between it and the main roll 1, making the coated surface of the web W smooth and smooth. It can be finished to a glossy surface. Further, there is an advantage that there is no need to frequently wash the counter-rotating roll 2 even if it is operated for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an example of a roll coater according to the present invention, and FIG. 2 is a schematic side view showing a modification of the solvent supply means in the roll coater according to the present invention. 1...Main roll, 2...Reverse rotation roll, 3...
Coating agent reservoir, 4... Doctor, 5... Solvent supply means, 6... Solvent supply member, 7... Solvent reservoir.

Claims (1)

[Claims] 1. A main roll 1 that guides and runs the web W, and a counter-rotating roll 2 that rotates in the opposite direction to the main roll 1 at a contact point P' with the main roll 1. , 2, and the roll coater passes the web W through the nip between both rolls 1 and 2 and applies the coating agent from the coating agent reservoir 3 onto the web W. The doctor 4 that acts on the circumferential surface of the roll 2 is disposed at a position on the lower side in the roll rotation direction than the coating agent reservoir 3, and on the lower side in the roll rotation direction than the point of action P of the doctor 4 on the circumference of the counter-rotating roll 2. A roll coater characterized in that a means 5 for supplying a solvent to the circumferential surface of a counter-rotating roll 2 is provided at a side portion.